1. Field of the Invention
The present invention relates to a stepping motor control apparatus for controlling a stepping motor.
2. Description of the Prior Art
Stepping motors have prevailed as low-cost motors that control a position or a speed.
As for a stepping motor control apparatus that controls the stepping motor, when only a current flowing through the motor is monitored, neither the position of a magnetic pole in the stepping motor nor the rotating speed thereof is monitored. A loss of synchronism or vibrations may occur in the stepping motor.
Therefore, the conventional stepping motor control apparatus is provided with an angle detector that detects the position of the magnetic pole in the stepping motor.
However, the inclusion of the angle detector increases the size of the stepping motor. Moreover, the cost of manufacture increases.
Another conventional stepping motor control apparatus does not include an angle detector that detects the position of a magnetic pole. A constant relevant to a winding is set to a fixed value or a nominal value, whereby the position of the magnetic pole is calculated.
However, when a constant relevant to a winding is set to a fixed value or a nominal value, the position of a magnetic pole in a stepping motor cannot be calculated accurately. Therefore, a loss of synchronism or vibrations may occur in the stepping motor.